The average mark across all the areas assessed was 33.6, out of a possible 51.

In England, the average mark was 34.5 in 2017.

Girls in West Sussex did better than boys, scoring on average 1.8 more points.

Rosamund McNeil, assistant general secretary at the National Education Union, considered the assessment positive in terms of helping teachers and parents know more about children’s capabilities.

She said: “The purpose of this assessment is to gather information and help teachers plan the next stage for that child. Practitioners are really supportive of it and they are very worried because they feel the Government does not like it because it is not just limited to numeracy and literacy.”

Commenting on the better performance by girls, she added: “Gender is one of the factors, but not critical at this stage. You also have to take into account that 20 per cent of the kids may have some additional need and it really matters which month in the year children were born.

“Every child develops at a different pace from the age of three to 18, and that is something that everybody has to understand.”